Lord John Lamont Quackett, the true identity of Fantomallard, was a gentleman thief from Duckburg during the 1920s. When Donald Duck found his diary in Villa Rosa, this inspired him to become The Duck Avenger.
Guido Martina scarcely used the character, since his role was limited to be Donald's inspiration, but Italian Disney comic artist and writer Marco Gervasio expanded on the character and his background, at first as part of flashbacks in Duck Avenger stories and later with a mini-series happening in the past. Fantomius lived in Villa Rosa with his fiancée and partner in crime Dolly Duck a.k.a. Dolly Paprika.
Some Danish comics show an aged yet still living FantomAllard who returns to Duckburg to test his successor, but he mistakenly believes Gladstone Gander to be the Duck Avenger, as Gladstone was the original inheritor of Villa Rosa.